U.S. patent application number 16/786760 was filed with the patent office on 2020-06-04 for method for operating a pharmacy order-picking system.
The applicant listed for this patent is CareFusion Germany 326 GmbH. Invention is credited to Andreas BAUSE, Christoph HELLENBRAND, Andreas KLAPPERICH, Dennis REIF.
Application Number | 20200175568 16/786760 |
Document ID | / |
Family ID | 47633111 |
Filed Date | 2020-06-04 |
United States Patent
Application |
20200175568 |
Kind Code |
A1 |
HELLENBRAND; Christoph ; et
al. |
June 4, 2020 |
METHOD FOR OPERATING A PHARMACY ORDER-PICKING SYSTEM
Abstract
The present disclosure relates to a method for operating a
pharmacy order-picking device. The present method reduces the
susceptibility of the pharmacy order-picking device to disruption.
To detect a positioning deviation of the control appliance in the
horizontal direction, at least one desired value of at least one
reference position is made available, the control appliance is
brought to a position corresponding to the desired value in the
horizontal direction and, when a signal characteristic of a
reference position is detected, an actual value of this reference
position is determined. A desired value is compared with a
corresponding actual value, or two actual values are compared with
each other, and a deviation is determined. If a deviation is
determined that exceeds a limit value, a signal pointing to the
need for a correction is output. Depending on the deviation,
automatic correction of the position deviation can be
performed.
Inventors: |
HELLENBRAND; Christoph;
(Kaifenheim, DE) ; KLAPPERICH; Andreas; (Rieden,
DE) ; BAUSE; Andreas; (Kruft, DE) ; REIF;
Dennis; (Kaisersesch, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CareFusion Germany 326 GmbH |
Kelberg |
|
DE |
|
|
Family ID: |
47633111 |
Appl. No.: |
16/786760 |
Filed: |
February 10, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14382308 |
Aug 29, 2014 |
10559021 |
|
|
PCT/EP2013/052286 |
Feb 6, 2013 |
|
|
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16786760 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06Q 30/0633 20130101;
G06Q 50/22 20130101; B65G 1/0421 20130101; G06Q 10/0836
20130101 |
International
Class: |
G06Q 30/06 20060101
G06Q030/06; B65G 1/04 20060101 B65G001/04; G06Q 10/08 20060101
G06Q010/08; G06Q 50/22 20060101 G06Q050/22 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 29, 2012 |
EP |
12157483.4 |
Claims
1. A machine-implemented method for detecting a positioning
deviation of an operating unit in a pharmacy order-picking system,
the method comprising: accessing a setpoint value corresponding to
a reference position, the reference position comprising a physical
location in the pharmacy order-picking system; approaching, using
the operating unit, in a horizontal direction, the reference
position; detecting a signal that is characteristic of the
reference position; ascertaining an actual value of the reference
position; comparing the setpoint value with the actual value;
determining a horizontal deviation based on the comparison of the
setpoint value and the actual value; and if the horizontal
deviation exceeds a threshold value, outputting a signal indicating
a need for a correction.
2. The method of claim 1, further comprising: accessing a second
setpoint value corresponding to a second reference position;
approaching, using the operating unit, in a vertical direction, the
second reference position; detecting a second signal that is
characteristic of the second reference position; ascertaining a
second actual value of the second reference position; comparing the
second setpoint value with the second actual value; determining a
vertical deviation based on the comparison of the second setpoint
value and the second actual value; and if the vertical deviation
exceeds the threshold value, outputting a signal indicating the
need for a correction.
3. The method of claim 2, further comprising: rotating the
operating unit by a predefined value C on detection of a
positioning deviation of the operating unit with respect to a
vertical axis of rotation after detection of the horizontal
deviation; approaching, using the operating unit, a third reference
position corresponding to a third setpoint value; detecting a third
signal that is characteristic of the third reference position;
ascertaining a third actual value of the third reference position;
comparing the third setpoint value with the third actual value;
determining a second horizontal deviation based on the third
setpoint value and the third actual value; and if the horizontal
deviation and the second horizontal deviation exceed the threshold
value, or if the horizontal deviation and the second horizontal
deviation differ by a predefined value, outputting the signal
indicating the need for the correction.
4. The method of claim 1, further comprising: responsive to
outputting the signal indicating correction is needed, transmitting
a service query electronically to a service employee; and shutting
down the pharmacy-order picking system.
5. The method of claim 1, wherein the pharmacy order-picking system
comprises a control unit, and setpoint values are stored as
predefined values in the control unit.
6. The method of claim 1, wherein the pharmacy order-picking system
comprises a control unit, and the method further comprises: upon an
initial startup of operation of the pharmacy order-picking system,
approaching predefined reference positions; detecting a signal that
is characteristic of each of the predefined reference positions;
ascertaining a setpoint value; and storing the ascertained value in
the control unit.
7. The method of claim 1, further comprising: approaching the
reference position at a first speed until the setpoint value is
reached; and approaching the reference position at a second speed
until the signal that is characteristic of the reference position
is reached, wherein the second speed is lower than the first
speed.
8. A method for operating a pharmacy order-picking system, the
method comprising: ascertaining an actual value of a reference
position, the reference position comprising a physical location in
the pharmacy order-picking system; comparing the actual value of
the reference position with a stored setpoint value corresponding
to the reference position; determining a horizontal deviation based
on the comparison of the stored setpoint value and the actual
value; and if the horizontal deviation exceeds a threshold value,
outputting a signal indicating correction is needed.
9. The method of claim 8, further comprising: ascertaining a second
actual value of a second reference position; comparing the second
actual value with a second stored setpoint value corresponding to
the second reference position; determining a vertical deviation
based on the comparison of the second stored setpoint value and the
second actual value; and if the vertical deviation exceeds a
threshold value, outputting a signal indicating correction is
needed.
10. The method of claim 8, further comprising: responsive to
outputting the signal indicating correction is needed, transmitting
a service query electronically to a service employee; and shutting
down the pharmacy-order picking system.
11. The method of claim 8, wherein the pharmacy order-picking
system comprises a control unit, and setpoint values are stored as
predefined values in the control unit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/382,308, filed on Aug. 29, 2014, which is the U.S.
National Phase under 35 U.S.C. .sctn. 371 of International
Application No. PCT/EP2013/052286, filed on Feb. 6, 2013, which
claims the benefit of EP 12157483.4, filed Feb. 29, 2012. The
entire contents of these applications are incorporated by reference
herein.
BACKGROUND
[0002] In some pharmacy order-picking systems, a large number of
different drug packages of various sizes (piece goods) may be
stored on elongated shelves in a chaotic fashion that is optimized
as to space. Some pharmacy-order picking systems place drug
packages on the shelves and/or retrieve them from the shelves with
the help of an operating unit, wherein the operating unit has a
gripping device for gripping the drug packages. For placing the
drug packages on a shelf, the drug packages are identified,
measured (e.g., the measurements are determined in three
dimensions) and conveyed into a gripping area of the gripping
device of a shelf operating system (see DE 195 09 951 C2, for
example).
SUMMARY
[0003] The present disclosure relates to a method for operating a
pharmacy order-picking system with at least one shelf unit, each
shelf unit having a plurality of shelves extending in a horizontal
direction (X axis) and a plurality of shelf walls extending in a
vertical direction (Z axis), at least one operating device being
movable horizontally and vertically in front of the row of shelves
and having a gripping device for placing drug packages on the
shelves and/or retrieving them from the shelves, wherein the
operating unit has at least one sensor and has a control unit
connected to the operating unit.
[0004] Based on the measurements of the drug packages to be stored
as well as the occupancy of the pharmacy order-picking system,
optimal storage sites for the drug packages are calculated and
stored in the control unit. To calculate an optimal storage site,
it may also be necessary for the control unit to know the precise
geometric structure of the pharmacy order-picking systems, and in
particular, the location and/or arrangement and dimensions of the
shelves and walls. In this way is it possible, for example, to
prevent a position that is occupied by a wall from being selected
within the pharmacy order-picking system. The location of a drug
package is calculated as space coordinates (with an X, Y, Z axis
component) within the pharmacy order-picking system. The reference
point (origin) for these space coordinates may be, for example, a
certain reference point within the device (for example, certain
position of the operating unit/gripping device). Each shelving
compartment may be formed by shelves and dividers to have its own
reference point. The position (and/or the space coordinates) of a
drug package is/are then determined within the shelving compartment
just as uniquely based on the space coordinates of the reference
point of the compartment and the space coordinate of the drug
package within the shelving compartment.
[0005] For further storage, the gripping device grips the drug
packages in the gripping area and conveys them to the predetermined
storage site. For optimal utilization of space, the shelves are
occupied densely but drug packages of different dimensions and
different types may be stored side by side.
[0006] If a certain drug package is to be retrieved from
storage--for example, because of a request by a customer of the
pharmacy--the operating unit selects the storage site of the
desired drug package, grips the drug package with the griping
device, and transfers it to a discharge point and/or to a
conveyance mechanism, which conveys the drug package to a discharge
point (for example, in the sales room of a pharmacy). Conveyance
might not be necessary, depending on the structural situation.
[0007] The accuracy of the positioning of the operating unit and/or
the gripping device in storage/retrieval from storage is desired
for smooth operation of the pharmacy order-picking system. When
placing an item on the shelf, for example, the control unit
calculates a storage location with certain space coordinates on the
basis of the geometry of the pharmacy order-picking system, the
dimensions of the drug package to be placed on the shelf and the
occupancy of the system. This storage site is to be approached by
the operating unit, and the drug package is to be placed on a shelf
at the calculated storage site. Inaccurate positioning of the
operating unit may prevent fault-free placement on the shelf (for
example, if a position that includes a shelving wall is approached
or if the shelving position thus approached is already occupied).
Based on retrieval from storage, inaccurate positioning of the
operating unit and the gripping device means that it may be
impossible under some circumstances to retrieve a certain drug
package from storage using the operating unit, and in some
situations it may be necessary to retrieve a drug package by hand,
which thus leads to unwanted delays and a disturbance in automatic
operation.
[0008] The operating unit itself is a complex mechanical device
having a plurality of drive mechanisms, which make it possible for
the operating unit and the gripping device to move in both
horizontal and vertical directions (X and Z axes). During operation
of the pharmacy order-picking system, the operating unit and the
gripping device are exposed to high loads, which may result in a
creeping loss of accuracy with which the operating unit can be
positioned with respect to a given location within the system.
[0009] If the drive mechanism for positioning in X direction, for
example, includes one or more toothed belts, these belts may become
stretched out over time. That is, the toothed belt undergoes a
change in length. If the stretched toothed belt is then driven by a
corresponding motor (for example, a stepping motor) to the storage
site by the same number of steps that would be necessary for
positioning if the toothed belt were not stretched out, this would
result in a mistake in the positioning in X direction (the actual
position may not be reached because of the stretched length of the
toothed belt). Depending on the precise design of the drive
mechanisms, additional problems may also prevent accurate
positioning. Inaccurate positioning of the operating unit thus
causes a disturbance in automatic (continuous) operation of a
pharmacy order-picking system because there is the risk that the
drug packages cannot be placed on the shelf and retrieved with the
operating unit.
[0010] The object of the present disclosure is therefore to provide
a method for operating a pharmacy order-picking system which will
prevent susceptibility to disturbances in automatic operation of
the pharmacy order-picking system.
[0011] The pharmacy order-picking system, which is operated
according to the disclosure includes at least one shelf unit, each
having a plurality of shelves extending in a horizontal direction
and a plurality of shelving walls extending in a vertical
direction, at least one operating unit that can be moved
horizontally and vertically in front of the shelving, having a
gripping device for placing drug packages on the shelf and/or
retrieving them from the shelf, such that the operating unit has at
least one sensor and a control unit, which is connected to the
operating unit controls all of the operating sequences within the
pharmacy order-picking system.
[0012] For operation of a pharmacy order-picking system in a method
described herein for operating a pharmacy order-picking system, at
least one setpoint value of at least one reference position is made
available for detection of a deviation in positioning of the
operating unit in the horizontal direction (X axis).
[0013] A reference position with regard to the X axis may be the
position of a certain shelving wall within the pharmacy
order-picking system, for example. The setpoint value then
characterizes the distance of the reference position from a
reference point within the pharmacy order-picking system. If two
setpoint values of two reference positions are supplied, then the
reference positions can correspond to the arrangements of two
shelving walls within the pharmacy order-picking system. Other
points may also be selected as reference positions. It is important
that these positions do not undergo any spatial change in the
course of operation.
[0014] Due to the type of installed drive mechanism for the
movement of the operating unit in X direction as well as its
characteristics, the control unit knows how to approach (for
example, with X motor steps when using a stepping motor) a
reference position with a predefined precision in a "faultless"
drive mechanism (e.g., having "origin characteristics").
[0015] In a method described herein, a position corresponding to a
setpoint value is approached by the operating units in the
horizontal direction, wherein the aforementioned position deviates
from the setpoint value of the reference position. That is, the
position being approached is behind or in front of the actual
reference position.
[0016] With the sensor turned on (the sensor may not be turned on
until reaching the position corresponding to the setpoint value or
it is in a continuous operating state), the operating unit is
advanced further in the horizontal direction toward the actual
setpoint value, and an actual value of this reference position is
determined when a signal that is characteristic of the reference
position is detected by the sensor. The sensor may be an optical
sensor according to the triangulation principle, for example, which
can determine the distance of the sensor from an object by which
the sensor passes. The actual value that is determined indicates
the space coordinates that have been determined (or at least the X
component thereof) of the reference position at the point in time
of the determination of the actual value.
[0017] A setpoint value is compared with a corresponding actual
value--or two actual values are compared with one another--and the
deviation is determined. Apart from the negligible thermal
expansion, the absolute location of the reference position(s)
within the pharmacy order-picking system. In the ideal case (which
corresponds to the original condition, for example, in which the
setpoint values were determined), the actual value is identical to
the setpoint value. However, if a deviation is found, this means
that a different number of motor steps would be needed for
reaching/approaching the reference position(s) in X direction (when
using a stepping motor, for example). The positioning is no longer
accurate if the control unit is running a control program that
presupposes faultless, e.g., undisturbed drive mechanism(s). X
motor steps may be taken until reaching a certain reference
position if the drive mechanism is not disturbed. However, if the
drive mechanism is disturbed, X+.DELTA.X or X-.DELTA.X motor steps
may be taken until reaching the reference point. Therefore, if one
does not have knowledge of the disturbance, the wrong position is
approached by .DELTA.X steps.
[0018] If two actual values are compared with one another, then a
deviation indicates that a number of motor steps different from
what is expected (when using a stepping motor, for example) would
be necessary for traveling the distance between the two reference
points in X direction. This deviation also indicates that
positioning based on the control program present in the control
unit is no longer precise.
[0019] If a deviation exceeding the limit value is detected, then a
signal indicating the need for a correction is output.
[0020] A method described herein reduces the need for manual
retrieval of a drug package and reduces the susceptibility of the
system in that checks are performed at predefined intervals to
ascertain whether the positioning in X direction is still precise
enough. If this is not the case, then a corresponding signal is
output, and this signal may vary, depending on the type and size of
the deviation, for example. When there are only minor deviations,
an internal adjustment can be made to ensure continuation of
automatic operation.
[0021] With a pharmacy order-picking system, the X-direction/X-axis
is usually the direction in which the operating unit moves
horizontally. Depending on how the drug packages are placed on the
shelf, the X axis is usually also the longest axis, which has the
resulting effect that the operating unit is often moved
particularly frequently along this axis and deviations in the
positioning accuracy can have especially strong effects.
[0022] In a preferred embodiment of a method described herein, in
addition to detecting a position deviation in the horizontal
direction (X axis) the Z axis (vertical axis) is also investigated
with regard to a position deviation.
[0023] To do so, at least one setpoint value of at least one
reference position is made available. This may be, for example, the
location of one or more shelves. With the operating unit, a
position corresponding to the setpoint value is approached, and
with the sensor turned on, the gripping device is moved further to
the setpoint value and on detecting a signal that is characteristic
of the reference position, the actual value of this reference
position is determined. A setpoint value is then compared with a
corresponding actual value or two actual values are compared with
one another and the deviation if any is determined. If a deviation
exceeding a limit value is ascertained, then a signal indicating
the need for a correction is output, and this signal may vary with
the type and size of the deviation.
[0024] Due to the enormous variety of pharmaceutical drugs, i a
large variety of different drug packages may be on hand. Therefore,
a large storage area within the pharmacy order-picking system may
be desired. This may be achieved by widening the device in the X
and/or Z directions, for example. Another possibility is to install
two shelving areas, usually in parallel. Each shelf unit may be
assigned its own operating unit, but in view of the cost-intensive
components of the operating unit, it is preferable to install only
one operating unit. To be able to operate both shelf units, it is
necessary for the gripping device of the operating unit to be
rotatable by at least 180.degree. (C. axis), so that both shelf
units can be operated from the front for placing items on the shelf
and retrieving them from the shelf. Even if the gripping device can
rotate about the C axis, there may be deviations in positioning,
for example, such that the device is rotated not by 180.degree. but
instead by 180.degree.+X.degree. or 180.degree..times.X.degree.
(for example, due to slippage of the rotary motor when the rotation
is too low).
[0025] Therefore, in a preferred embodiment of a method described
herein, the rotation about the C axis is also tested. The pharmacy
order-picking system, which is operated with the preferred
embodiment of a method described herein, includes at least two
parallel shelf units between which the operating unit can be moved
horizontally and vertically, such that the gripping device of the
operating unit can be rotated and/or pivoted about the vertical
axis.
[0026] For detecting a positioning deviation in the gripping device
with respect to the C axis of rotation, first a check is performed,
as already described above, with respect to the positioning
deviation in the X direction in relation to one of the shelf units.
The gripping device is then rotated by a predefined value C such
that this value in the ideal case (without interference in the
rotation about the C axis of rotation) induces a rotation by
180.degree..
[0027] A check is performed as to whether there is a deviation in
positioning in the X direction in the second shelf unit. Therefore,
a second position corresponding to a second setpoint value is
approached by the operating unit for the second shelf unit (thus at
least one reference position in X direction is supplied per shelf
unit). With the sensor turned on, the gripping device is advanced
further to the setpoint value, and when a signal that is
characteristic of the second reference position is detected, the
actual value of the reference position is ascertained. The setpoint
value of the second reference position is compared with the actual
value, and the deviation, if any, is determined. If the deviations
thereby ascertained with respect to the first and second shelf
units exceed the limit values or if they differ by a predefined
value, a signal is output indicating the need for a correction,
such that the signal varies as a function of the deviations thereby
ascertained.
[0028] Deviations in the position accuracy with regard to the C
axis are thus not ascertained directly thereon but instead are
ascertained indirectly based on positioning deviations with respect
to the X axis of the shelf units.
[0029] The operating unit can usually be moved in both horizontal
and vertical directions with the help of guide rails. Depending on
the design of the pharmacy order-picking system, two horizontal
guide rails are used, such that the vertical guide rail is guided
horizontally with the gripping device on these guide rails. Each
guide rail may be assigned an independent drive mechanism (or one
section of a central drive mechanism), and the drive mechanisms
ensure movement (preferably in synchronization) along the
horizontal guide rails.
[0030] If the drive mechanisms do not move in synchronization on
the vertical guide rail, this may lead to an inclined position of
the vertical guide rail, and such an inclined position will in turn
influence the positioning accuracy of the operating unit and of the
gripping device.
[0031] In a preferred embodiment of a method described herein, a
setpoint value of at least one reference position is made
available; with this setpoint value, the operating unit approaches
a position corresponding to the setpoint values for detecting an
inclined position of the operating unit for the upper and lower
guide rails; on detection of a signal that is characteristic of a
reference position, one actual value is ascertained per reference
position, and the setpoint values are compared with the actual
values, one deviation being ascertained for each reference
position. Finally, if the deviations thereby ascertained differ by
more than a predefined limit value, a signal indicating the need
for a correction is output, such that this signal depends on the
size of the differential value.
[0032] In a preferred embodiment of a method described herein, a
service query is transmitted electronically to a service employee
and/or the pharmacy order-picking system is shut down, depending on
the signal indicating the need for a correction. A service query
may be transmitted when the deviations/differences detected exceed
the predefined limit values, but a malfunction of the system can be
largely ruled out. Maintenance of the system may be initiated in
this way before it is necessary to shut down the system and
necessary for the user to intervene.
[0033] The setpoint value(s) may be made available by saving the
setpoint value(s) as predefined values in the control unit. This
procedure is extremely simple and can be implemented quickly but
may utilize a very high measure of manufacturing precision. It is
preferable for the setpoint value(s) of at least one reference
position to be made available by the fact that the setpoint
value(s) is/are learned. For example, after the initial startup of
operation of the pharmacy order-picking system in that predefined
reference positions are approached and, on detection of a signal
that is characteristic of a certain reference position, a value is
ascertained, this value being saved as the setpoint value in the
control unit.
[0034] In the case of large-scale pharmacies in particular, the
pharmacy order-picking system is more or less in continuous
operation, so that it is desirable for a method described herein to
be implementable as rapidly as possible. Therefore, in a preferred
embodiment of a method described herein, a position corresponding
to a setpoint value is approached at a first speed v1 and the
operating unit is moved further in the direction of the reference
position at a second speed v2 until a signal that is characteristic
of the reference position is detected, such that speed v2 is less
than speed v1.
[0035] The operating unit may be driven at full speed, for example,
to the position corresponding to the setpoint value. If the sensor
is not operating continuously, the sensor can be turned on. The
operating unit is moved further at a reduced speed until a signal
that is characteristic of the reference position is detected. The
reduced speed contributes toward an increase in measurement
accuracy, and the combination with a distance traveled at full
speed permits a rapid and at the same time reliable implementation
of the method.
[0036] The deviations in positioning may be caused by a variety of
factors, which are described in further detail below, so that it is
not necessarily possible to conclude the cause from the deviations
ascertained. However, to the extent that it is definite and the
basis of the deviations ascertained, causing the deviation in
positioning, in a preferred embodiment of a method described
herein, one or more corresponding correction factors are
ascertained is/are ascertained on the basis of the deviation(s)
detected, these correction factors are stored in the control unit
and control programs executed subsequently take this/these
correction factor(s) into account in controlling the operating
unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] A method described herein is described in greater detail
below on the basis of preferred embodiments that are shown only
schematically in the drawings, in which:
[0038] FIG. 1 illustrates a lateral sectional view of a shelf unit
of a pharmacy order-picking system.
[0039] FIG. 2 illustrates a top view of a pharmacy order-picking
system.
[0040] FIG. 3 illustrates a sectional view of a pharmacy
order-picking system.
[0041] FIGS. 4a-4c illustrate sectional views of a section of a
pharmacy order-picking system, wherein the figures are to be used
to illustrate a method described herein.
[0042] FIG. 5a-5b illustrate sectional views of one section of a
pharmacy order-picking system, wherein the figures are supposed to
illustrate a method described herein.
[0043] FIG. 6 illustrates a schematic view of one section of a
pharmacy order-picking system wherein the figure should serve to
illustrate a method described herein.
DETAILED DESCRIPTION
[0044] FIG. 1 illustrates a lateral sectional view of a pharmacy
order-picking system having two shelf units, but only one shelf
unit 10 is shown here. The pharmacy order-picking system also
includes an operating unit 20 that can be moved horizontally and
vertically between the shelf units 10. The shelf units each
comprise a plurality of shelves 11 extending in the horizontal
direction (X axis) and a plurality of shelf walls 12 extending in
the vertical direction (Z axis). The shelves 11 are usually made
completely of glass with a smooth surface. Drug packages 22 are
stored in a chaotic fashion on the shelves 11 with optimal
utilization of space.
[0045] The operating unit 20 can be moved horizontally and
vertically between shelf units 10 with the help of two horizontal
guide rails (13a, 13b) and one vertical guide rail (14) and the
drive units assigned to them. The vertical guide rail 14 is movably
attached to the horizontal guide rails 13a, 13b for this purpose.
The operating unit 20 includes a gripping device 21, which can be
moved vertically on the guide rail 14 by means of a corresponding
drive mechanism as well as a gripper jaw and/or a vacuum gripper.
The gripping device 21 also includes a sensor 23 with which the
distance from the sensor to the back wall (see FIG. 2) of the shelf
unit, stored drug packages 22 or components of a shelf unit (shelf
walls, shelves), can be determined.
[0046] The sensor 23 may be, for example, an optical sensor
according to the triangulation method which determines the distance
from the plane spanned by the two horizontal guides at a 90.degree.
angle (ideal value, positioning deviations possible; see FIGS. 5a,
5b in this regard). In another embodiment, an inductive proximity
sensor may be used, with metallic reference points to be used in
this case.
[0047] The operating unit 20 is electronically connected to a
control unit 30, which is shown only schematically here. The
control unit 30 may comprise a plurality of computers (not shown)
and controls the entire operation of the system (identification,
placement on a shelf and retrieval from the shelf, etc.).
[0048] With the pharmacy order-picking system shown in FIG. 1,
seven reference positions (X1, X2, X3, X4, X5, Z1, Z2) are provided
(reference position X4 is situated on the shelf unit, which is not
shown and therefore is not "visible" in FIG. 1). However, this
number of reference positions may be necessary when all of the
positioning deviations described below are to be ascertained--in
other embodiments, it may be adequate to have only one reference
position.
[0049] Reference positions may be provided by any points that can
be detected by the sensor within the pharmacy order-picking system.
In the following description of the method, it is assumed that the
reference positions are provided by shelves (positions Z1, Z2) and
walls (positions X1, X2, X3, X4, X5). The reference positions in
this case are therefore not additional structural measures. In
other embodiments the reference positions may also be provided by
specific components (signal generators, etc.).
[0050] FIG. 2 illustrates a top view of a section of a pharmacy
order-picking system wherein the two parallel shelf units 10, 10a
are visible in this figure, with the operating unit 20 being
movable horizontally and vertically between them with the help of
the guide rails 13a, 13b, 14. For placing drug packages on the
shelf or retrieving them from the shelf, the gripping device 21 of
the operating unit 20 is aligned at a 90.degree. angle to the back
wall 16, 16a of the corresponding shelf unit 10, 10a. The operating
unit 20 is itself high-maintenance and cost-intensive, so it is
customary to install just one operating unit for two parallel shelf
units in a pharmacy order-picking system. To be able to operate the
two shelf units, the gripping device can be rotated about an axis
of rotation C, as indicated in FIG. 2. The reference position X4,
which is not "visible" in FIG. 1, is provided by a component of the
shelf unit 10a (shelf wall 12).
[0051] FIG. 3 illustrates a sectional view of the pharmacy
order-picking system. The operating unit 20 can be moved
horizontally and vertically on guide rails 13a, 13b between the two
shelf units 10, 10a. Those skilled in the art are familiar with
details of how the operating unit can be moved on the guide rails,
so these details are not essential to the present disclosure. The
vertical guide rail 14 is usually moved on the horizontal guide
rails 13a, 13b with the help of one or two toothed belts and one or
more drives. Likewise, the gripping device 21 together with the
sensor 23 is usually moved vertically on the vertical guide rail 14
with the help of a toothed belt and a corresponding drive.
[0052] With reference to FIGS. 4a-4c, 5a-5b and 6, embodiments of a
method described herein are described below. The diagrams of
sections of a pharmacy order-picking system selected to illustrate
a method described herein are highly schematic, in order not to
obscure the nature of a method described herein due to unnecessary
structural details.
[0053] X-Axis Positioning Deviation
[0054] With reference to FIGS. 4a-4c, one embodiment of a method
described herein is described below, this embodiment regarding
positioning deviations with regard to the X axis.
[0055] A positioning deviation with respect to the X axis can be
detected in general on the basis of one reference point (based on a
benchmark). However, no conclusion can be drawn about the type of
deviation on the basis of this one deviation detected (elongation
in length of toothed belts, mechanical slippage, etc.). Therefore,
an embodiment of a method described herein, in which two reference
points (X2, X3) for ascertaining a positioning deviation are
verified, is described below.
[0056] FIGS. 4a-4c illustrate a schematic sectional view of one
section of a pharmacy order-picking system having two shelf units
10, 10a and one operating unit that can be moved horizontally and
vertically between the shelf units; only the gripping device 21 is
indicated schematically for the sake of simplicity. The view
according to the aforementioned figures shows the lower portion of
the pharmacy order-picking system, and therefore only the reference
positions X2, X3 and X4 are indicated.
[0057] The numerical data given in the figures refer to the X
component of the space coordinates of various reference positions,
where only the numbers that are intended to illustrate the method
as such.
[0058] In a method described herein for operating a pharmacy
order-picking system, two setpoint values X.sub.2S, X.sub.3S for
the reference positions X2, X3 of shelf unit 10a are provided for
detecting a position deviation of the operating unit in the
horizontal direction (X axis). The setpoint values of the
aforementioned reference positions are each embodied in FIGS. 4a-4c
in the unit labeled as "setpoint" at the left (X.sub.2S=10,
X.sub.3S=45).
[0059] As mentioned above, the setpoint values mentioned above can
be provided by storing them only in the memory of the control unit
or by having them learned at the time of (initial) start of
operation of the pharmacy order-picking system. In the (initial)
start of operation, the operating unit is therefore moved from a
reference position, the position of which is predetermined (e.g.,
the "zero point" of the operating unit) at a first speed
(preferably the maximum speed of the operating unit in the X
direction) to a preliminary position X.sub.2V which corresponds to
the first setpoint value X.sub.2S. Beyond this preliminary position
X.sub.2V, the operating unit with the sensor turned on is moved
further in the direction of the reference position X2. As soon as
the reference position has been reached, the sensor detects a
characteristic signal. In the exemplary embodiment shown here, the
reference position X2 is provided by a shelf wall, and the sensor
detects a characteristic signal (change in flank in the digital
output signal or change in level with an analog output signal). The
space coordinates (or at least the X component thereof) is saved as
the setpoint value X.sub.2S for the reference position X2.
Accordingly, the movement is performed using the reference position
X3, and it is not necessary to return the operating unit to the
reference point. According to FIG. 4a, the reference positions X2
and X3 are approached from the left. However, that is not
necessary. In the method, it is irrelevant from which side the
reference positions are approached with the sensor turned on.
[0060] After providing the setpoint values for the reference
positions X2, X3, the operating unit 20 approaches a position
corresponding to the setpoint value X.sub.2S in the horizontal
direction. The aforementioned position X.sub.2V is situated at X
coordinate 5. With the sensor turned on, the operating unit is now
moved further toward the setpoint value and on detecting a signal
that is characteristic of the reference position X2, an actual
value X.sub.2I is ascertained for the reference position X2. As
soon as the actual value for the reference position has been
ascertained, the operating unit is moved to a position X.sub.3V
corresponding to the setpoint value X3 and the operating unit 20 is
moved further in the direction of the reference position X3
starting from this position, and on detecting a signal that is
characteristic of the reference position X3, an actual value
X.sub.3I for this reference position is ascertained.
[0061] The actual values X.sub.2I, X.sub.3I thereby ascertained are
compared with the corresponding setpoint values X.sub.2S, X.sub.3S
and one deviation is ascertained per reference position X2 and X3
(A.sub.X2, A.sub.X3). A deviation may also be determined by
subtracting the two actual values thereby ascertained for the
reference positions X2, X3 from one another (e.g., the distance
between the actual values X.sub.2I, X.sub.3I is ascertained) and
the value thereby ascertain is compared with the difference in the
corresponding setpoint values.
[0062] If a deviation A.sub.X2, A.sub.X3, A.sub.X23 which exceeds
the limit value is ascertained, a signal indicating the need for a
correction is output. For example, it may be displayed to the user
that a positioning deviation with respect to the X axis has been
ascertained and the service has been informed accordingly. If the
deviations thereby ascertained no longer allow reliable operation
of the system, the system is stopped and the service is
informed.
[0063] The deviations thereby ascertained allow inferences
regarding the type of disturbance in the positioning accuracy. In
the case illustrated in FIG. 4a, the actual values for the
reference positions X2, X3 correspond to the setpoint values. It
follows from this that there is not any disturbance in the
positioning accuracy with regard to the X axis. In the case
illustrated in FIG. 34b, a deviation A.sub.X2=1 is ascertained with
respect to the reference position X2, and a deviation A.sub.X3=5 is
ascertained with regard to the reference position X3, from which it
is possible to conclude that there has been an elongation in the
length of the tooth belt(s) of the drive mechanism for the X axis.
On the basis of the deviations thereby ascertained, a correction
factor which can be used in the further positioning of the
operating unit may be ascertained.
[0064] In the case illustrated in FIG. 4c, a deviation A.sub.X2,
A.sub.X3=2 is ascertained for each of the two reference positions
X2, X3. It follows from this that there is no elongation in the
length of the toothed belt(s) of the drive mechanism for the
movement of the operating unit in the X direction, but there is an
offset which indicates a mechanical slippage or a jumping of the
tooth belt over a corresponding drive gear.
[0065] C Axis Positioning Deviation (Axis of Rotation of the
Gripping Device and the Operating Unit)
[0066] With reference to FIGS. 4a, 5a, 5b, one embodiment of a
method described herein is described below in which the positioning
accuracy with regard to the C axis (axis of rotation of the
gripping device of the operating unit) is ascertained.
[0067] In this embodiment of a method described herein, first the
setpoint values for the reference positions X3, X4 are provided as
described above. Next the positioning deviation with regard to the
reference X3 is ascertained in the manner already described with
reference to the X axis. A position deviation with regard to the X
axis is then ascertained at a reference position X4 of the other
shelf unit 10.
[0068] To do so, the grouping device 21 of the operating unit is
rotated by a predetermined value C with this rotation by the
predetermined value C corresponds to a rotation by 180.degree. in
the ideal case. Then a second position X.sub.4V corresponding to a
second setpoint value X.sub.4S is approached with the operating
unit. In the schematic diagrams shown in FIGS. 4a, 5a-5b, this
position X.sub.4V is at the right of the reference X4. With the
sensor turned on, the operating unit is then moved further in the
direction of the reference position X4, and an actual value
X.sub.4I of the reference position is ascertained on detecting a
signal that is characteristic of the reference position X4. Next,
the setpoint value of the second reference position X4 is compared
with the actual value and a deviation A.sub.X4 is determined. If
the deviations ascertained for the reference positions X3 and X4
exceed limit values or if they are different by a predefined value,
then a signal indicating the need for a correction is output.
[0069] The type of positioning deviation can be deduced from the
ascertained deviations A.sub.X3, A.sub.X4. In the case illustrated
in FIG. 4a, the deviations for the reference positions X3 and X4
are both the same (they are both 0), which means that there is no
positioning deviation with respect to the C axis of rotation (if
other positioning deviations with respect to the X axis can be
ruled out).
[0070] FIG. 5a illustrates a case in which the gripping device 21
is not oriented at a 90.degree. angle to the shelf unit 10a but
instead the angle to the shelf unit is adjusted slightly clockwise.
In determining the actual value for the reference position X3,
therefore this is not detected at X=45 (as would be the case with a
90.degree. angle), but instead is detected only at X=46. After
rotation at the gripping device 21 by a value C (corresponding to
the ideal angle of 180.degree. in this case), the actual value for
the reference position X4 is determined. Based on the faulty
positioning of the gripping device with respect to the shelf unit
10, the actual value of the reference position at x=44 is
determined. A comparison at the setpoint values with the actual
values for the reference positions X3, X4 shows that the deviations
are the same (A.sub.X3, A.sub.X4) and are greater than 0, which
indicates a false position of the gripping device 21 with respect
to the shelf walls.
[0071] FIG. 5b illustrates a case in which the rotation by the
amount C is not rotation by 180.degree. but instead is by a reduced
angle. With regard to the reference position X3, a deviation of
A.sub.X3=0 is determined and for the reference position X4, a
deviation of A.sub.X4=1 is determined. If faultless positioning
with regard to the X axis is assumed, this means that the rotation
by the value C does not result in rotation by 180.degree., so that
positioning accuracy with regard to the C axis is disturbed.
[0072] Z-Axis Positioning Deviation
[0073] Referring to FIG. 6, one embodiment of a method described
herein will now be described briefly. In this embodiment a
positioning deviation with regard to the Z axis is also
determined.
[0074] A positioning deviation with regard to the Z axis can be
determined in general according to the positioning deviation with
regard to the X axis. That is, either a positioning deviation
starting from a reference point is determined with respect to the
reference positions Z1, Z2 or a difference in the actual values of
the reference points Z1, Z2 is determined and this is compared with
the difference between the setpoint values of the reference points
Z1 and/or Z2. If a deviation between the difference in the setpoint
values and actual values is detected, one can conclude from this
that there has been an increase in the length of a tooth belt that
has been used, if any, for positioning the gripping device 21. The
details regarding the performance of the method for determining a
positioning deviation in the Z axis are comparable with those of
the method for determining a positioning deviation with regard to
the X axis, so that a renewed detailed presentation will not be
given here.
[0075] To determine whether there is an inclined position of the
vertical guide rail, positioning deviations in two reference
positions with different Z axis positions are determined. In the
present case, a possible inclined position of the Z axis can be
determined, in which positioning deviations with regard to the X
axis are determined for the reference positions X1, X2 or X3, X5.
In the determining of a possible inclined position of the Z axis,
the two measured reference positions should be situated on a shelf
unit to rule out possible influences due to a positioning deviation
with regard to the C axis of rotation of the gripping device. The
possible positioning deviations with regard to the two reference
positions are compared and in the event of a deviation in these
from one another, an inclined position of the Z axis (vertical
guide rail) can be concluded and when a limit value is exceeded, a
signal indicating the need for a correction is output.
* * * * *